1 #include <string.h>
2 #include <stdio.h>
3
4 char b[50];
5
reset_b(void)6 void reset_b(void)
7 {
8 int i;
9
10 for (i = 0; i < 50; i++)
11 b[i] = '_';
12 b[49] = '\0';
13 }
14
reset_b2(void)15 void reset_b2(void)
16 {
17 reset_b();
18 strcpy(b, "ABCDEFG");
19 }
20
main(void)21 int main(void)
22 {
23 char x[100];
24 char a[] = "abcdefghijklmnopqrstuvwxyz";
25 int i;
26
27 /* testing memcpy/strcpy overlap */
28
29 for (i = 0; i < 50; i++) {
30 x[i] = i+1; // don't put any zeroes in there
31 }
32 for (i = 50; i < 100; i++) {
33 // because of the errors, the strcpy's will overrun, so put some
34 // zeroes in the second half to stop them eventually
35 x[i] = 0;
36
37 }
38
39 memcpy(x+20, x, 20); // ok
40 memcpy(x+20, x, 21); // overlap
41 memcpy(x, x+20, 20); // ok
42 memcpy(x, x+20, 21); // overlap
43
44 strncpy(x+20, x, 20); // ok
45 strncpy(x+20, x, 21); // overlap
46 strncpy(x, x+20, 20); // ok
47 strncpy(x, x+20, 21); // overlap
48
49 x[39] = '\0';
50 strcpy(x, x+20); // ok
51
52 x[39] = 39;
53 x[40] = '\0';
54 strcpy(x, x+20); // overlap
55
56 x[19] = '\0';
57 strcpy(x+20, x); // ok
58
59 /*
60 x[19] = 19;
61 x[20] = '\0';
62 strcpy(x+20, x); // overlap, but runs forever (or until it seg faults)
63 */
64
65 /* testing strcpy, strncpy() */
66
67 reset_b();
68 printf("`%s'\n", b);
69
70 strcpy(b, a);
71 printf("`%s'\n", b);
72
73 reset_b();
74 strncpy(b, a, 25);
75 printf("`%s'\n", b);
76
77 reset_b();
78 strncpy(b, a, 26);
79 printf("`%s'\n", b);
80
81 reset_b();
82 strncpy(b, a, 27);
83 printf("`%s'\n", b);
84
85 printf("\n");
86
87 /* testing strncat() */
88
89 reset_b2();
90 printf("`%s'\n", b);
91
92 reset_b2();
93 strcat(b, a);
94 printf("`%s'\n", b);
95
96 reset_b2();
97 strncat(b, a, 25);
98 printf("`%s'\n", b);
99
100 reset_b2();
101 strncat(b, a, 26);
102 printf("`%s'\n", b);
103
104 reset_b2();
105 strncat(b, a, 27);
106 printf("`%s'\n", b);
107
108 /* Nb: can't actually get strcat warning -- if any overlap occurs, it will
109 always run forever, I think... */
110
111 for ( i = 0; i < 2; i++)
112 strncat(a+20, a, 21); // run twice to check 2nd error isn't shown
113 strncat(a, a+20, 21);
114
115 /* This is ok, but once gave a warning when strncpy() was wrong,
116 and used 'n' for the length, even when the src was shorter than 'n' */
117 {
118 char dest[64];
119 char src [16];
120 strcpy( src, "short" );
121 strncpy( dest, src, 20 );
122 }
123
124 return 0;
125 }
126